* follow up to #9104
* relates to #8790
* fix up styleguide example buttons for yes/no variants, add more disabled variants
* add type="button" to styleguide example buttons
* revert box-sizing change and use line-height with calc for borders instead
* revise border overrides to set border-color only
* fix modal button override
- relates to #9104
- Removed: .button-neutral, .button-strokeonhover and .hover-no.
- Replaced hardcoded font size, font weight values with theme variables.
- Removed overridden duplicate styles for .yes, .no and .bicolor.
- Merged a few styles under one class.
- Removed non-link button which was using span tag from styleguide, remove other unhelpful examples
- Tweak stylesheets for compatibility with latest stylelint configuration
- Move stylelint config to JS for ease of copying rules with main config
- Enforce scss/no-global-function-names by refactoring code with sass-migrator
- Run Sass code through sass-migrator
- Change stylelint configuration and code to enforce font-family-no-missing-generic-family-keyword
- Manually switch to math.div where migrator used * 0.5
